var MongoClient = require('mongodb').MongoClient;
var url = 'mongodb://localhost/EmployeeDB';
var ObjectId = require('mongodb').ObjectId;
MongoClient.connect(url, function(err, db) {
db.collection('collection_name').findOne({
_id:ObjectId("61412a7bf30b9 .... ") /// doc _id
}).then(r=>{
console.log(r.item)
});
});